JP2005048845A - Rolling screw device - Google Patents

Abstract

A rolling screw device that improves the durability of a device by preventing a rolling element from colliding with a counterbore in which an end deflector is mounted is provided.
An area 10a from a thread groove end portion 12a on an inner peripheral surface of a counterbore 20 to a rolling element guide path provided in an end deflector 6 has a ball 16 rolling on the rolling element rolling path 22 at an end. This is a raceway surface that rolls toward the rolling element guide path of the deflector 6. The raceway surface 20a is formed in a curved surface shape with a radius of curvature such that the ratio to the diameter of the ball 16 is 0.5 or more. As a result, even if a rolling screw device is used at high speed and high acceleration / deceleration, the balls 16 pass while rolling without colliding with the raceway surface 20a, so that excessive stress is not concentrated on the raceway surface 20a. There is no risk of affecting the life of the rolling screw device.
[Selection] Figure 2

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rolling screw device such as a ball screw and a roller screw used as a machine part for converting a rotational motion of a motor or the like into a linear motion, for example, in a machine tool feeding device, etc. The present invention relates to a rolling screw device.
[0002]
[Prior art]
A rolling screw device used in a machine tool feeder or the like includes a screw shaft having a spiral rolling element thread groove on the outer peripheral surface, and a spiral rolling element thread groove facing the rolling element thread groove of the screw shaft. When the screw shaft or one of the nuts rotates around the shaft, a large number of rolling elements incorporated in the nut are moved between the rolling element screw grooves of both the screw shaft and the nut. It rolls the formed rolling element rolling path, and a nut or a screw shaft carries out a linear motion in connection with this.
[0003]
Such a rolling screw device is provided with a rolling element circulation component that infinitely circulates the rolling elements rolling on the rolling element rolling path. In the internal circulation type rolling screw device disclosed in Patent Document 1, FIG. And the end deflector 6 shown in FIG. 5 is used. The end deflector 6 is a member provided with the rolling element guiding path 2 and the tongue 4 and is mounted in a counterbore 10 provided on the end surface of the nut 8 as shown in FIG.
[0004]
The end deflector 6 attached to the counterbore 10 will be described with reference to FIGS.
The rolling element screw groove 12 formed in a spiral shape on the inner peripheral surface of the nut 8 is interrupted on the peripheral surface of the counterbore 10 (a portion indicated by reference numeral 12a and referred to as a screw groove end portion 12a). Further, one end opening 14 a of the rolling element return passage 14 provided in the axial direction of the nut 8 is opened on the bottom surface of the counterbore 10.
[0005]
In the end deflector 6, one opening 2 a of the rolling element guide path 2 that is open on the tongue 4 side faces the screw groove end 12 a of the rolling element thread groove 12, and the other end of the rolling element guide path 2. The opening 2b is mounted in the counterbore 10 so as to communicate with the one end opening 14a of the rolling element return passage 14, and the rolling element rolling path (the rolling element screw groove 12 and a rolling element screw of a screw shaft not shown). The rolling element 16 that has rolled the groove) is brought into contact with the tip of the tongue 4 to be introduced into the rolling element guide path 2 and returned to the rolling element return path 14.
Here, a region 10a from the thread groove end portion 12a on the inner peripheral surface of the counterbore 10 to one opening 2a of the rolling element guide path 2 is formed in a curved shape, and has been rolling on the rolling element guide path. The rolling element 16 is a raceway surface that rolls toward one opening 2a of the rolling element guide path 2 of the end deflector 6 (hereinafter referred to as a raceway surface 10a).
[0006]
[Patent Document 1]
Utility Model Registration No. 3034052 [0007]
[Problems to be solved by the invention]
By the way, in the rolling screw device of Patent Document 1 used at high speed and high acceleration / deceleration, the rolling element 16 that has rolled on the rolling element rolling path is close to the thread groove end portion 12a of the rolling element screw groove 12, that is, , It easily collides with the aforementioned track surface 10a and passes through. This is because, as shown in FIG. 7, since the radius of curvature R ₁ of the raceway surface 10a is set to a value smaller than the radius (Dw / 2) of the rolling elements 16.
As described above, when the rolling elements 16 continue to collide with the raceway surface 10a, excessive stress is concentrated on the raceway surface 10a, causing a sag. As a result, the life of the rolling screw device may be significantly affected.
The present invention has been made paying attention to such problems, and prevents rolling elements from colliding with a counterbore in which an end deflector is mounted, thereby improving the durability of the apparatus. An object is to provide a screw device.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a rolling screw device according to the present invention includes a screw shaft having a rolling element screw groove on an outer peripheral surface, and a nut having a rolling element screw groove facing the rolling element screw groove on an inner peripheral surface. A plurality of rolling elements that roll with rolling motion of the screw shaft or the nut on a rolling element rolling path formed by the rolling element screw groove of the screw shaft and the rolling element screw groove of the nut; A rolling element return passage formed inside to return the rolling element to the rolling element rolling path, a counterbore hole formed in an end surface of the nut, and mounted on the counterbore hole, the rolling element rolling path is An end deflector provided with a rolling element guide path for guiding the rolling element that has been rolling to the rolling element return path, and the seat from the portion where the rolling element screw groove of the nut is interrupted to the rolling element guide path The inner surface of the counterbore, and the rolling element guideway A rolling screw device having a raceway surface that rolls the rolling element that has been moved toward the rolling element guide path, and the curvature of the raceway surface with respect to the diameter of the rolling element is 0.5 or more. The apparatus is characterized by being formed into a curved surface shape having a radius.
[0009]
According to such a configuration, since the raceway surface is formed in a curved surface shape having a radius of curvature with a ratio to the diameter of the rolling element of 0.5 or more, the rolling element that has rolled on the rolling element rolling path is loose. Rolling on the raceway surface inclined in the direction of, the collision with the raceway surface is avoided. Therefore, even if the rolling screw device is used at high speed and high acceleration / deceleration, excessive stress is not concentrated on the raceway surface, and there is no possibility of affecting the life of the rolling screw device.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of a rolling screw device according to the present invention will be described in detail.
First, the overall configuration of the rolling screw device according to the present invention will be described with reference to FIGS. 1 and 2. The same components as those shown in FIGS. 4 to 7 are denoted by the same reference numerals.
As shown in FIG. 1, the rolling screw device of the present invention includes a screw shaft 18, a cylindrical nut 8 that relatively moves in the axial direction of the screw shaft 18, and a large number of rolling elements incorporated in the nut 8. Ball 16.
The screw shaft 18 has a circular cross section perpendicular to the axial direction, and a spiral rolling element thread groove 20 is formed on the outer peripheral surface of the screw shaft 18 from one end to the other end of the screw shaft 18. It is formed over.
[0011]
The nut 8 has an inner peripheral surface facing the outer peripheral surface of the screw shaft 18, and the rolling element thread groove 12 is formed on the inner peripheral surface of the nut 8. Further, the nut 8 is formed to be relatively thick, and a rolling element return passage 14 is formed in the nut 8 along the axial direction of the nut 8.
The rolling element screw groove 12 of the nut 8 and the rolling element screw groove 20 of the screw shaft 18 are opposed to each other. When one of the screw shaft 18 and the nut 8 rotates around the axis, the ball 16 is rolled. It rolls on a rolling element rolling path 22 formed between the moving element screw grooves 12 and 20.
[0012]
End deflectors 6 for infinite circulation of the balls 16 are attached to both ends of the nut 8.
The end deflector 6 is formed by, for example, injection molding a resin material into a predetermined shape, and is a member provided with rolling element guide paths 2 and tongues 4 as shown in FIGS. 4 and 5.
As shown in FIG. 2, the end deflector 6 is mounted in a counterbore 24 formed on the end surface of the nut 8.
The rolling element screw groove 12 of the nut 8 is interrupted at the peripheral surface of the counterbore hole 24, and this interrupted portion is referred to as a thread groove end portion 12a. Further, one end opening portion 14 a of the rolling element return passage 14 provided in the axial direction of the nut 8 is opened on the bottom surface of the counterbore hole 24.
[0013]
In the end deflector 6, one opening 2 a of the rolling element guide path 2 that is open on the tongue 4 side faces the screw groove end 12 a of the rolling element thread groove 12, and the other end of the rolling element guide path 2. The opening 16 is mounted in the counterbore 24 so that the opening 2 b communicates with the one end opening 14 a of the rolling element return passage 14, and the ball 16 rolling on the rolling element rolling path 22 is attached to the tip of the tongue 4. It comes into contact and is introduced into the rolling element guide path 2 and returned to the rolling element return path 14.
[0014]
Here, a region 24a from the thread groove end portion 12a on the inner peripheral surface of the counterbore hole 24 to one opening 2a of the rolling element guide path 2 ends the ball 16 that has rolled on the rolling element rolling path 22. This is a raceway surface 24 a that rolls toward one opening 2 a of the rolling element guide path 2 of the deflector 6.
The raceway surface 24a is machined into a curved surface shape with a radius of curvature R that satisfies the following expression (1), for example.
R / Dw ≧ 0.5 (1)
Where R: radius of curvature of raceway surface Dw: diameter of ball
When the raceway surface 24a is formed so as to satisfy the range of the above formula (1), as shown in FIG. 3, the ball 16 rolling on the rolling element rolling path 22 rolls on the gently inclined raceway surface 24a. Thus, the collision with the raceway surface 24a is avoided.
Therefore, since the raceway surface 24a is formed into a curved surface having a radius of curvature with a ratio to the diameter of the ball 16 of 0.5 or more, even if a rolling screw device is used at high speed and high acceleration / deceleration, the raceway surface 24a Since the ball 16 passes while rolling without colliding, excessive stress is not concentrated on the raceway surface 24a, and there is no possibility of affecting the life of the rolling screw device.
[0016]
Here, the boundary part between the thread groove end portion 12a of the rolling element thread groove 12 and the raceway surface 24a has an edge shape of a V groove, and the ball 16 rolls at a high speed from the rolling element rolling path 22. When the ball 16 contacts and passes through the boundary portion of the edge shape, the boundary portion and the ball 16 may be peeled and damaged.
Therefore, in order to prevent separation damage of the boundary portion and the ball 16, it is preferable to process the raceway surface 24a into a curved surface shape with a radius of curvature R that satisfies the following equation (2).
R / Dw ≧ 1.0 (2)
Where R: radius of curvature of raceway surface Dw: diameter of ball
As described above, when the raceway surface 24a is formed into a curved surface shape having a radius of curvature such that the ratio to the diameter of the ball 16 is 1.0 or more, the inclination angle of the rolling element screw groove 12 to the screw groove end portion 12a becomes gentle. Since the rolling speed of the ball 16 is reduced and the ball 16 comes into contact with the boundary portion with a small force, peeling damage between the boundary portion and the ball 16 can be suppressed.
The present invention is not limited to the embodiment described above. For example, in the present embodiment, the ball 16 is exemplified as the rolling element, but the roller 16 is not limited to the ball.
[0018]
【The invention's effect】
As described above, according to the rolling screw device of the present invention, the raceway surface is formed in a curved surface shape having a radius of curvature with a ratio to the ball diameter of 0.5 or more. Since the moving ball rolls and passes through the gently inclined track surface, collision with the track surface is avoided. Therefore, even if the rolling screw device is used at high speed and high acceleration / deceleration, excessive stress is not concentrated on the raceway surface, and there is no possibility of affecting the life of the rolling screw device.
[Brief description of the drawings]
FIG. 1 is a view showing a rolling screw device according to the present invention.
FIG. 2 is a view of attaching an end deflector to a counterbore formed in the end face of the nut according to the present invention.
FIG. 3 is a view showing the shape of a raceway surface formed on the inner surface of a counterbore according to the present invention.
FIG. 4 is a view showing an end deflector according to the present invention from the tongue side.
FIG. 5 is a view showing an end deflector according to the present invention from the back side with respect to the front side on which a tongue is formed.
FIG. 6 is a view of attaching an end deflector to a counterbore having a conventional structure.
FIG. 7 is a view showing the shape of a raceway surface formed on the inner surface of a counterbore hole having a conventional structure.
[Explanation of symbols]
2 Rolling element guide path 6 End deflector 8 Nut 12 Nut rolling element thread groove 12a End of rolling element thread groove of nut (part interrupted by counterbore of rolling element thread groove of nut)
14 Rolling body return passage 16 Ball (rolling body)
18 Screw shaft 20 Rolling body thread groove 22 of the screw shaft Rolling body rolling path 24 Counterbore 24a Raceway surface

Claims (1)

A screw shaft having a rolling element thread groove on an outer peripheral surface, a nut having a rolling element thread groove facing the rolling element thread groove on an inner peripheral surface, a rolling element thread groove of the screw shaft, and a rolling element thread groove of the nut. A number of rolling elements that roll with the rotational movement of the screw shaft or the nut, and a rolling element that is formed inside the nut and returns the rolling element to the rolling element rolling path. A rolling element return passage, a counterbore hole formed in the end face of the nut, and a counter bore that is mounted in the counterbore hole and that has rolled the rolling element rolling path to guide the rolling element return passage. An end deflector provided with a rolling element guiding path, and an inner surface of the counterbore from the portion where the rolling element screw groove of the nut is interrupted to the rolling element guiding path, and has been rolling the rolling element guiding path The rolling element is rolled toward the rolling element guide path. In screw device rolling including a raceway surface that, the,
A rolling screw device characterized in that the raceway surface is formed into a curved surface having a radius of curvature with a ratio to the diameter of the rolling element of 0.5 or more.

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